Crane



T. N. GARSON.

CRANE.

APPLICATION FILED SEPT. 20, 1918.

' Patented Apr. 20, 1920.

, rnoavariiiit-enson, or NEW roux, 2;. Y.

To all whom it may concern:

Be it known that I, THORVALD N. GARsoN, a citizen of the United States, residing in New York city, in the county and State of New York, have invented certain new and useful Improvements in Cranes, of which the following is a specification.

This invention relates particularly to that class of crane which forms the subject of my Patent No. 1,228,659 of June 5, 1917, its characteristic being the provision of a single hoisting rope for the load and boom, two

' interengaging membersbeing located at the base of the boom for automatically locking the latter in any elevated position to permit the lowering of the hoisting rope. The object of the present improvement is to provide a heavy-duty crane of this class, for instance a locomotive or' heavy truck crane capable of handling a load of five.tons or more. The characteristic of the present improvement is the combination of the mast,

boom and interengaging boom-locking members in such relationship that the boom' in its reaction upon the said locking members is a lever of the second class only, and thus the strain upon the locking members is reduced to a minimum. Furthermore, when the said interengaging locking members consist of a ratchet and pawl, as in the embodiment of the invention hereinafter described, the size-(and hence-strength) oftheratchet teeth and pawl may be 'largely'increased over the corresponding parts when acted'upon by the boom as a leverqof the first class. 4

The invention will be understood by reference to the accompanying} drawing, in which:

Figure 1 is a side elevation of a truck crane embodying the invention; and

Fig. 2 is a plan view of the crane.

In the present embodiment of the invention the crane is mounted upon an electric truck A, the supporting frame B for the crane being disposed at the rear end of the truck. As in'the construction described in my 'aforesaid patent, the mast comprises a central stationary shaft. C, which in this instance is tubular, and the rotary vertical channeled plates 1 which are secured near their upper ends to a bearing 2 surrounding the shaft. The plates 1 also are secured to a lower bearing member 3, intermediate which and a bearing block 4-may be dis- Application filed Scpteniberfifl, 1918. Serial No. 254,892.

' Specification 61' r lzer Pram; Pate ted. Apr. 20, 1920.

posed a series of rollers-or ball bearings end of the boom, the rope then being looped,

about the pulley of abloc'k 13, and its end being secured at 1 1 to the boom. It will be seen that thewinding in of the hoisting rope will raise theload until the contact 13 of.

block 13 meets wear plate 15 at the end of the booin. The boom then will be raised, so that the load will be swung back toward the mast, the boom finally reaching the positionshown in dotted lines'E, Fig. 1. In order that the load may be lowered upon the truck at the point over which it is swung by the boom, means are provided for automatically locking the boom in its elevated position to permit a reverse movement of the hoisting rope. The said means will now be described.

It will be seen from the accompanying drawing'that the bracket 7 is provided with a segment rack 7* which is located intermediate the pivotal point 6 of the boom and the free end of the latter. The said rack is engaged by a pawl 16 carried by a shaft 17 which, in this instance is journaled in bearing bosses 18 depending from the bars 5 comprising theboomQ To shaft 17 is fixed a lever arm 19 connected by a cable 20 with slide bar 21 having a handle 21 by means of which the pawl may be moved out of engagement with the ratchet against the tension-of a'spring 22. It will be understood that, if desired, the ratchet-segment may be placed on the boom and the pawl on the bracket '5, and that any other suitable interengaging locking members may be substituted for the ratchet and pawl construction just described.

Slightly in advance of the pivotal connection of the boom with the bracket 7 the latter is provided with a bearing roller 23 which is adapted to run upon the annular bearing block 4; as a trackway and thus serves to relieve both the mast and the lower or thrust bearing of strains. It will be noted that the crane is so mounted as to be capable of a. complete revolution about the bearing shaft C. This is of great ad crane may be revolved by suitable operative connections with the source of power.,

It will be seen that for a given vertical movement of the boom the locking members 16, 7* have a greater relative movement comparatively with similar locking members when disposed intermediate the pivotal point 6 and the mast. Thus when the locking-members consist of a segment rack and pawl, the teeth of the rack may be made of substantial size and depth, and likewise, the pawl may be made of a size to resist great strain. And inasmuch as in the present construction the boom when carrying the load acts upon the locking members as a lever of the second class only, the capacity of the crane is very largely increased, as-will be understood without further explanation.

What I claim is:

In a crane, the combination with a support, of a hoisting drum and driving means therefor, a boom pivotally mounted upon the support, a hoisting rope connected with the drum and led over the end of the boom, means including the hoisting rope tor raising the boom, and two inter-engaging members. one carried by said support and one carried by the boom, and disposed intermediate the pivotal connection of the boom and the "free end of the latter, for automatically locking the boom in its elevated position. whereby the boom will react upon the said interengaging members as a lover of the second class.

Signed at New York, county and State oi- New York, this 7th day of September, 1918.

THORVALD N. GARSON.

\Vitnesses \V. LEE HEL'Ms, ELLEN P. DORAN. 

